School of Earth Sciences - Theses
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ItemEnvironmental fate and transport of TNT in soil at the former explosives factory Maribyrnong( 2002)Highly toxic explosives compounds can potentially contaminate soil and groundwater and pose extended environmental hazard due to their persistence. Explosives contamination within soils was investigated at the former Explosives Factory at Maribyrnong (EFM), by sampling and spectrophotometric / HPLC analysis. The environmental fate and transport of 2,4,6-trinitrotoluene (TNT) was assessed via batch and microcosm testing to quantify the influence of key subsurface sinks, adsorption, and transformation, and hence evaluate natural attenuation as a remediation option. A five tonne crystalline TNT source zone was delineated within soils at the base of a TNT process waste lagoon. This source was found to be supplying aqueous TNT loading to subsurface soils and groundwater, with the resultant plume localised to the shallow clay sequence due to a combination of natural attenuation processes and hydrogeological constraints. Freundlich described sorptive partitioning was found to be the main TNT sink at EFM (KF= 29 mL/g), while transformation rates were moderate (3.86 x 10-4 hr-1) due to aerobic conditions, and TNT toxicity inhibiting microbial degradation. Slow groundwater migration toward the Maribyrnong River (0.7 m/yr) and upward hydraulic gradients within underlying sand and gravel aquifers serve to increase TNT residence time within the clay aquitard, leading to increased interaction with adsorptive substrates and microbes and/or elements of the soil matrix responsible for aerobic transformation. Remediation of the contaminated lagoon may involve removal and treatment/landfilling of the top 1m of soil, then refilling with an impermeable capping allowing ongoing natural attenuation of residual TNT at depth via anaerobic degradation and sorption.
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ItemThe hydrogeology of the Gippsland Basin, and its role in the genesis and accumulation of petroleum( 2002)The Gippsland Basin of southeastern Australia is the most energy-rich basin of Australia producing petroleum, gas and brown coal. Three-quarters of the Basin lies offshore and the rest onshore. The basin was initiated as a rift valley, caused by the separation of the Australian continent from the Antarctic followed by a number of tectonic events throughout the basin history. Early Cretaceous sedimentary rocks form the basement, which is in turn covered with Late Cretaceous to Recent sediment of sand, clay, limestone, and brown coal seams. The total thickness of the in-filling sediments offshore attains up to 6000 m, but onshore is up to 1200 m. There are three main acquifer systems, the Hydrostratigraphic Units 2, 4, and 7, all of which are confined. The two lower aquifer systems, Units 4 and 7, contain high temperature groundwater. It is generally agreed that the hydrocarbons offshore have been derived from terrestrial matters including brown coal and ligneous clay offshore. In the present study, the author has developed a case that hydrocarbons offshore being derived not only from the offshore source but also from onshore brown coals and coaly matter and in this hydrocarbon forming processes, groundwater has played a significant role. The Central Deep, in particular, provides favourable conditions for hydrocarbon maturation. Throughout the basin history, the Central Deep has experienced the oil window temperatures. In supporting this hypothesis, geochemical studies on groundwater, brown coal, and hydrocarbons as well as hydrodynamics are presented.
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ItemGeologic and geomorphic applications of Aster satellite imagery, northern Flinders Ranges, South Australia( 2002)Multispectal ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite data has been evaluated for geologic and geomorphic interpretations within the northern Flinders Ranges, South Australia. ASTER is a new remote sensing imaging system on board NASA’s Terra satellite, launched in December, 1999. ASTER measures the reflectance of the Earth’s surface within 14 bandwidths of the visible, near infrared, short wave infrared and thermal infrared sections of the electromagnetic spectrum, with a minimum spatial resolution of 15 m. ASTER has the ability to produce digital elevation models (DEM), important for understanding the dynamics of the landscape by draping false colour images over topography. The northern Flinders Ranges is one of the most diverse geological settings on the Australian continent, making it an ideal ‘test site’ to demonstrate the capabilities of the ASTER instrument. The area contains a range of geology from Precambrian basement to Quaternary desert landforms. The ability of ASTER Level 1B data to discriminate between the large range of lithologies is assessed. Geomorphic interpretations made from exploiting the high resolution ASTER data and DEM has revealed a significant record of post Pliocene landscape development, attributed to a combination of climatic and tectonic factors. Such features as incision morphology and the identification of palaeodrainages have enabled constraints to be placed on the Quaternary degradational and aggradational events. For example, estimates of Quaternary sediment flux rates in some areas of the study area are essentially extracted from ASTER DEM data. ASTER has persisted to be extremely useful in the study of aeolian landform morphology in regions surrounding the northern Flinders Ranges. The short wave infrared has proved useful for identifying areas of high surface moisture, directly relating to the depth to water table. The application of principal component analysis to ASTER short wave infrared data is used to accurately identify specific mineralogical character.
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ItemThe thermotectonic evolution of the northern precambrian shield, Western Australia( 2002)Reconnaissance 40Ar/39Ar dating of K-feldspars and muscovites, and fission track and (U-Th)/He thermochronometry on apatites has been applied to ~1 X 106 km2 of the northern Western Australian Shield. The study area includes the Archaean northern Yilgarn Craton and Pilbara Craton, and the intervening Proterozoic basins. The geomorphology of the study area also reveals a subdued relief, which is characteristic for Australian cratonic landscapes. The fact that the shield consists entirely of Precambrian rocks with low topographic relief has led to the widely held view that the West Australian Shield has been tectonically stable for a long period of time. (From Abstract)
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ItemOrigin and formation of Ordovician sedimentary phosphates at Phosphate Hill, Mansfield, southern Australia( 2002)Ordovician sedimentary phosphatic rocks were mined for fertilizer use in the 1920’s from a small, highly deformed belt of Ordovician rocks at Phosphate Hill, near Mansfield (Warburton, 1:250,000 topographical map). The formation of the phosphate and the environmental conditions at the time of its formation have not been previously discussed in detail. It is an example of a sedimentary phosphate deposit that displays the results of both primary phosphogenesis and secondary, reworking processes. The black shale lithologies are host to the primary phosphate formation in the form of concretionary phosphates, derived from the high phosphorous content of bottom waters and the shells of the phyllocarid crustacean Caryocaris. Caryocaris has been misidentified in previous studies and their importance as the dominant bioclast at Phosphate Hill, has not been realised until now. Phosphorous enrichment within the depositional environment resulted from the extremely high organic contents within marine waters, which is illustrated by the bituminous character of some of the black shale lithologies. The depositional environment was relatively low energy, with low sedimentation rates, in isolated and stagnant marine waters. Thin alternating shale and phosphatic sand lithologies were derived from changes in the energy levels of the depositional environment which led to small turbidity currents reworking the concretionary phosphates and forming clastic phosphatic grains. Phosphate Hill has been extensively folded, fractured and faulted, with near-surface exposure resulting in the episodic precipitation of alumino-phosphatic, hydrous mineral phases. Phosphate Hill is compositionally similar to the Cheshunt sedimentary phosphate occurrence in Victoria, reflecting a similarity in environmental conditions within the Ordovician depositional marine environment.